Up to now, a vehicle image signal processing apparatus that displays a vehicle surrounding image, which is acquired by an imaging device, on a display device is provided. In this case, when an image signal including, for example, a video indicating rear side of a vehicle which is a blind spot of a driver is input from the imaging device, the input image signal is decoded. The video included in the decoded image signal is processed, and the video that has been processed (processed video) is displayed on the display device. In the video processing, guide lines (for example, vehicle width extension lines, etc.), button keys, and so on are drawn for on-screen display in order to display the on-screen drawn video. In recent years, a first control unit and a second control unit are provided for the purpose of dispersing a processing load. In this configuration, when an accessory (ACC) power supply is switched from off to on, the first control unit starts activation firstly, and the second control unit starts activation after the first control unit completes the activation.
In a configuration where the first control unit and the second control unit are provided and the image processing is performed by the second control unit, the processed image cannot be displayed immediately after the accessory power supply is switched from off to on. Regarding this matter, Patent Literature 1 discloses a configuration in which when the accessory power supply is switched from off to on, unprocessed image (raw image) is displayed until the second control unit completes the activation, and the second control unit controls the processed image (image that has been processed) to be displayed after the second control unit completes the activation.
In the configuration of Patent Literature 1, after the second control unit completes the activation, the image signal output to the display device is switched from the image signal including the raw image to the image signal including the processed image, and the image display is switched from the raw image to the processed image. However, the above configuration suffers from such a problem that a black screen is unavoidably displayed when switching of the image signal, which is to be output to the display device, takes place. In other words, when switching the image display from the raw image to the processed image, the black screen is displayed on the display device.